In the field of minimally invasive surgery, for example diagnostic or therapeutic laparoscopy, an overpressure is generated in the abdomen by means of introduced gases (e.g., medical carbon dioxide (CO2)), said overpressure expanding the abdomen, in order that sufficient space is available for the visual inspection or the therapeutic procedure. For this purpose, so-called insufflators are used, which build up, by means of an adjusted gas flow, a controlled pressure in the abdomen. By a series of safety devices it is secured that the abdominal pressure is kept within limits, so that no tissue is damaged.
In the field of minimally invasive surgery, frequently electro-surgical devices or also lasers are used, the application of which will generate smoke in the abdomen. This smoke does not only obstruct the view, but contains contaminants (in the form of gases, droplets, and/or particles), so that this smoke has to be removed from the abdomen. A solution of this problem is that a simple outlet is formed, through which the flue gases exit from the body. A possibility of implementation for this is shown in U.S. Pat. No. 6,592,543. The extraction process is manually controlled by the surgeon by opening the valve at the trocar. However, current systems frequently produce larger amounts of smoke than at the date of filing of U.S. Pat. No. 6,592,543, so that the solution presented there cannot be used anymore today.
An improvement of such passive systems is achieved by providing an extraction device that can actively extract the gas in the abdomen including the smoke particles. Such a system is described, for instance, in U.S. Pat. No. 5,199,944. Therein, there is a problem that in a too strong extraction process of the flue gases, the pressure in the abdomen will decrease, so that the abdomen may collapse. The treating physician will then have to wait with the continuation of the surgery, until a sufficient pressure has built up again in the abdomen. It is easily understandable that such procedures have enormous disadvantages. On the other hand, in a too weak extraction process, it will not be effective enough, so that the surgeon is hindered by the poor vision, and the surgery will be prolonged. An alternative of this procedure is to re-supply the extracted gas to the patient (circulation). Such a system is described in the U.S. Pat. No. 4,735,603. In this embodiment, too, there is a problem that with too high extraction rate the abdominal pressure will decrease.
With high extraction capacity, the system pressure on the supply line will strongly increase. Depending on how narrow the connected instrument is, the pressure may increase to a higher or lower extent. In either case, at a certain pressure limit the supply line will open the safety valve within the supply line, and thus a pressure drop will be caused. Furthermore, the insufflator cannot supply additional carbon dioxide anymore, in order to compensate for likely existing leakages.
For an extraction process both with and without circulation, there is a problem that the extraction capacity under the actual conditions needs to be adjusted to the surgery. As described, the used instruments, but also the actual leakage rates at the abdomen play an important role here.
It is further state of the art that the surgeon is offered different stages for the extraction capacity at the device (for instance: low/medium/high). The surgeon is therefore responsible to decide the optimum extraction stage. Should the extraction capacity be adjusted too high, the insufflator cannot maintain the abdominal pressure. The surgeon will usually find out about that only when the pressure has already significantly decreased. Furthermore, it is difficult for the surgeon to find out beforehand that a higher extraction capacity is also possible. Possibly, the surgeon will then not select the higher extraction capacity, in order not to risk such a pressure drop.
There is therefore a need of a device for minimally invasive surgery, in particular laparoscopy, that allows to determine and to adjust the highest possible extraction rate for flue gases from the treatment space (in particular the abdomen), so that no significant pressure drop will occur in the mentioned volume. It is intended to be able to use the trocars available on the market. The solution of the problem is secured by the device according to the invention described in the following.